Exploring charge-transfer effects at metal-molecule interfaces through modeling surface-enhanced Raman spectroscopy...

Area of Science:

• Physical Chemistry
• Materials Science
• Spectroscopy

Background:

• Charge transfer (CT) at metal-molecule interfaces is crucial for catalysis, sensing, and energy applications.
• Surface-enhanced Raman spectroscopy (SERS) probes these interfaces by reflecting electronic structure changes influenced by CT.
• Modeling interfacial CT in large systems requires efficient electronic structure methods.

Purpose of the Study:

• To develop and present an efficient model for studying intrinsic charge transfer (CT) effects in SERS.
• To investigate the influence of molecular orientation and intermolecular interactions on interfacial CT using N-heterocyclic carbenes (NHCs).
• To apply the model to characterize the role of CT in tip-enhanced Raman scattering (TERS) molecular imaging.

Main Methods:

• Combining a simplified time-dependent density functional theory (TDDFT) approach with a first-principles Raman bond model.
• Partitioning Raman intensities into bond contributions to interpret SERS spectra as interatomic charge-flow modulations.
• Utilizing the Raman bond model to analyze molecular orientation, intermolecular interactions, and CT in NHC systems and TERS imaging.

Main Results:

• The developed model efficiently studies interfacial CT effects in SERS.
• Molecular orientation and intermolecular interactions significantly influence interfacial CT.
• The Raman bond model successfully characterizes the importance of interfacial CT in TERS imaging.

Conclusions:

• The Raman bond model, coupled with efficient first-principles calculations, provides a powerful tool for interpreting SERS spectra.
• This approach offers new insights into interfacial CT phenomena.
• The model enhances understanding of charge flow's role in molecular imaging techniques like TERS.